Mixture control for internal combustion engines



G. R. SISSON Aug. 23, 1938.

MIXTURE CONTROL FOR INTERNAL COMBUSTION ENGINES Filed April 23, 1931 5 Sheets-Sheet 1 mm Ma 5 5 P [W Aug. 23,

1938. e. R. SISSON MIXTURE CONTROL FOR INTERNAL COMBUSTION ENGINES Filed April 23, 1931 3 Sheets-Sheet 2 50 31 MP1 J 52 Mi orfl yfc gmeniio'c JAE/v P 5/5 .5 0M,

G. R. sl'ssoN Aug. 23, 1938.

MIXTURE CONTROL FOR INTERNAL COMBUSTION ENGINES Filed April 23: 1931 3 Sheets-Sheet 5 gwwmtot Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE MIXTURE CONTROL FOR INTERNAL GOM- BUSTION ENGINES 7 Claims.

My invention is concerned broadly with means for producing a temporary enrichment of the mixture supplied to an internal combustion engine while the engine is being started, and it is my object to produce such a device in which a single temperature-responsive means will control the proportions of the mixture both during and subsequent to the starting operation.

In my prior Patents Nos. 1,577,765, 1,577,766,

:and 1,544,350 I have illustrated means for tem- =tment on the devices of those prior patents.

In carrying out my invention I provide in association with the carburetor or other chargeforming device mechanism for controlling the proportions of the explosive mixture, such mechanism including an operating member movable in one direction to increase the proportion of fuel to air in the mixture and movable in the other direction to decrease such proportion. Associated with this mechanism I provide a temperature-responsive device which limits movement of the operating member in both directions in such a way that the operating member has a freedom of movement between the limits established by the temperature-responsive device.

The accompanying drawings illustrate several embodiments of my invention: Fig. 1 is an elevation of an internal combustion engine carburetor with its associated parts to which my invention has been applied; Fig. 2 is an elevation of a modified form of mixture-control device; Fig. 3 illustrates a slight modification of the device shown in Fig. 2; Fig. 4 illustrates a device of still another form; Fig. 6 is a View similar to Fig. 1 but illustrating my invention embodying the control device actuated by mechanical connection with the starting mechanism; Fig. 5 is an elevation of another form of electro-magnetically operated device; and Fig. 7 is a view similar to Figs. 1 and 5 showing a mixture- -control device which is free from connection with the engine-starting mechanism.

In Fig. 1, a carburetor II] is shown in association with the intake manifold H and exhaust manifold 12 of an internal combustion engine. The carburetor I is provided with a mixturecontrolling device, shown as a choke-valve [3 in the main air-inlet of the carburetor. As this valve is moved toward closed from open position,

it will cause a decrease in the amount of air supplied to the carburetor and also an increase in the quantity of fuel, the latter occurring as the result of the greater Vacuum to which the fueljet is subjected as the choke-valve is closed.

The choke-valve I3 is shown as biased to open position by means of a spring [4, and as movable toward closed position under the influence of a solenoid 15, the core 16 of which is operatively connected to the choke-valve. The winding of the solenoid I5 is conveniently connected in parallel with the starter-motor I! so that it is ren- 5 dered operative jointly with the starter-motor when the starter-motor switch 18 is closed.

For the purpose of limiting movements of the choke-valve l3 in accordance with temperature,

I provide a temperature-responsive element 20 20 which conveniently is in the form of a strip of bimetal fixed at one end to a bracket 2| by means of which it is held in position adjacent the exhaust manifold l2 of the engine where it will be generally responsive to engine-temperature. The free end of the bimetallic strip is connected through a link 22 to a control member 23 which is longitudinally slidable in a suitable guide 24 and which is provided with a cam slot 25. The core I6 is provided with an extension 26 which 30 overlies the control member 23 and carries a pin 27 that extends into the cam slot 25 in such control member.

The pin 21 is of a diameter considerably less than the width of the cam slot 25, and is normally held in contact with one side of such slot here shown as the left-hand side, by the action of the spring Hi. This side of the cam slot is sloped in such a manner that movement of the control member 23 as the temperature of the exhaust manifold l2 increases permits the spring 14 to move the choke-valve 13 toward open position. As long as the solenoid I5 is de-energized, the pin 27 will remain in engagement with the left-hand of the slot 25, and the position of the choke-valve l3 will depend upon the temperature of the exhaust manifold I2.

When the starter switch I8 is closed, the solenoid I5 is energized to draw the core IE to the right and thereby to move the choke-valve I3 toward closed position. This movement of the core IE will be limited by engagement of the pin 27 with the right-hand side of the slot 25. This side of the slot 25 is of a shape generally similar to that of the opposite side of the slot to permit greater closing movement of the choke-valve when the exhaust manifold I2 is comparatively cold.

In Fig. l, the parts of the device are shown in, the positions they occupy when the temperature of the engine is somewhere between cold and normal operative temperature. As the temperature of the engine decreases, the free end of the bimetallic strip 2K3 moves downwardly, and the side of the cam slot 25, acting through the pin 21, moves the choke-valve I3 toward closed position. The movement of the choke-valve thus produced is less than that necessary to cause its complete closing. If, with the engine cold, the starter switch I8 is closed to crank the engine, the solenoid 55 will be energized to draw the core It? to the right and complete closing movement of the choke-valve. Upon opening of the starter switch I8, the solenoid I5 will be de-energized, and the spring I4 will move the choke-valve I3 toward open position, its movement in this respect being limited by engagement of the pin 21 with the left-hand side of the slot 25. As the temperature of the engine increases, the free end of the bimetallic strip is and the control member 23 will move upwardly, thus permitting the spring 94 to move the choke-valve I3 nearer to open position. The parts are so proportioned that when the engine has reached normal operating temperature the choke-valve I3 will be substantially completely open.

If the engine is warm when the starter-switch i8 is closed, the resultant energization of the solenoid will not move the choke-valve to completely closed position; for this movement of the choke-valve will be limited by engagement of the pin 2? with the right-hand side of the slot 25. The partial closing of the choke-valve which is produced by energization of the solenoid I5 when the engine is hot is desirable; for a greatly enriched mixture is not only unnecessary but is usually undesirable when the engine is hot.

In the modification of my invention illustrated in Fig. 2, the choke-valve I3 of the carburetor I0 is cperatively connected to the armature of the electro-magnet 3i. The electro-magnet 3| and the parts associated therewith are conveniently located in an enclosing casing 32 adapted to be mounted adjacent the exhaust manifold of the engine or in any other position in which it will be generally subject to engine temperature. The armature 3G is pivoted as at 33 to one side of the casing 32 and extends across the pole of the magnet 3! in order to be drawn downwardly when the magnet 3! is energized. A spring 34 may be provided for biasing the armature 30 upwardly.

In the device illustrated in Fig. 2, the temperature-responsive element 35 is a spirally coiled bimetallic strip the inner end of which is anchored to a stud 36 on the casing 32 and the free end of which engages a vertically slidable member 3'5. Preferably, the end of the bimetallic strip and the member 3! are provided with co-operating abutments 35 and 3? adapted to be held in engagement by means of a spring 38 which acts between the member 31 and some fixed point.

At its upper end, the member 31 is provided with an abutment, conveniently in the form of a transverse pin 39 which overlies the armature 30 and limits its upward movement under the influence of the springs 34 and I 4. As the temperature to which the element 35 is subjected increases, such clement partially unwinds and permits upward movement of the member 31 under the influence of the spring 38. This movement of the member 3'! raises the abutment 39 and permits the spring I4 to move the choke-valve I3 toward open position.

For the purpose of limiting the closing movement of the choke-valve I3 which occurs when the magnet 3I is energized, I employ a wedge 40 which rests on the face of the pole of the magnet 3| and which is pivotally connected to the member 31 at a point below the plane of this poleface. The armature 30 is provided with an abutment 4| which is adapted to engage the upper surface of the wedge 40 to limit downward movement of the armature 30. As the member 31 moves upwardly under an increase in temperature, the wedge 40 will be moved slightly across the face of the pole of the magnet 3I toward the pivotal axis 33 of the armature 30. In addition, the wedge 40 will be rocked slightly in such a direction that its upper face, at the point where the abutment 4I engages it, will be raised. The net result of these two movements is that the extent to which the armature 30 is moved downwardly upon energization of the magnet 3I decreases with an increase in the temperature to which the element 35 is subjected.

As in the device illustrated in Fig. 1, the electromagnet 3I is connected in parallel with the starter motor IT. The circuit of the electro-magnet 3|, however, is shown as including a normally open magnetic switch 43. This switch is controlled jointly with the ignition switch 44 of the engine by the usual manually operated switch 45, the control being efiected in such a manner that the switch 43 will be closed when the ignition switch 45 is closed and open when the ignition switch is open.

Except for the effect of the magnetic switch 43, the device illustrated in Fig. 2 operates in substantially the same way as that shown in Fig. 1. That is, when the starter switch I8 is closed, the electro-magnet 3I and the starter motor I! are jointly energized. The energization of the magnet 3| draws the armature downwardly and moves the choke-valve I3 toward closed position, the movement of the choke-valve being limited by the position of the wedge 40. Upon opening of the starter switch I8, the magnet 3I is de-energized, and the armature 3!] moves upwardly under the influence of the springs I4 and 34 to open the choke-valve. Opening movement of the chokevalve is limited by the abutment 39 which moves upwardly and permits a greater opening of the choke-valve as the temperature of the engine increases. Because of the presence of the magnetic switch 43, the magnet 3I can not be energized and the choke-valve I3 can not be closed unless the ignition switch 45 is closed. This prevents the carburetor from being flooded if an attempt is made to start the engine without first closing the ignition switch.

The device illustrated in Fig. 3 is very similar to that shown in Fig. 2 except that the wedge 40, instead of being directly connected to the member 31 is connected thereto through a link 41. This device operates in substantially the same way as does the device shown in Fig. 2, upward movement of the member 3"! tilting the wedge 40 and decreasing the extent to which the chokevalve can be closed when the magnet 3I is energized.

In the device illustrated in Fig. 4, the temperature-responsive element 35, instead of operating a stop, co-operates with the electro-magnet 3| in the control of linkage which is operatively con- 7 nected to the choke-valve. For this purpose, the inner end of the element 35 is stationarily supported while the outer end bears against an abutment on a pivotally mounted arm 50. A link is pivotally connected to the outer end of the arm 50 and extends outwardly therefrom above the pole of the electro-magnet 3|, its outer end being connected through suitable operative connections 52 with the choke-valve [3 in such a way that downward movement of the outer end of the arm 5| will move the choke-valve toward closed position. The armature 30 of the electromagnet is pivotally mounted at one end and extends across the pole of the magnet. The armature 30 is connected with the link 5| in order that the link may be moved downwardly when the electro-magnet 3| is energized. To this end, the armature 30 may overlie a pin 53 or other abutment on the link 5|.

The parts described are conveniently mounted in an enclosing case 55 adapted to be mounted in such a position that the temperature-responsive element 35 will be generally responsive to the temperature of the engine.

In the upper wall of the casing 55 and directly above the link 5| there is an adjustable screw 56, the lower end of which engages the link 5| and serves as a fulcrum therefor when the magnet 3| is de-energized. The spring M, which is provided for the purpose of biasing the choke-valve |3 to open position, also serves normally to hold the link 5| in engagement with the lower end of the screw 56.

The electrical connections for the electro-magnet 3| are not shown in Fig. 4. Such connections may be arranged as indicated in Figs. 1 or 2, or they may be otherwise arranged to provide for energization of the magnet 3| jointly with the starter-motor of the engine.

When the magnet 3| is not energized, the link 5| occupies an elevated position illustrated approximately by the dotted lines in Fig. 4. In this condition, the spring l4 exerts an upward pull on the outer end of the link 5| and holds the link in engagement with the lower end of the screw 56. The inner end of the link exerts a downward pressure on the arm 50, tending to rotate such arm in a clockwise direction about its pivotal axis; but this tendency is opposed by the temperature-responsive element 35. As the engine temperature increases, the element 35 unwinds and permits the inner end of the link 5| to move downwardly and its outer end to move up wardly under the influence of the spring I4, with the result that the choke-valve I3 is moved toward open position. If the engine temperature decreases, as it would if the engine were idle, the element 35 would'swing the arm 50 in a counterclockwise direction to raise the inner end of the link 5|, lower the outer end of such link, and to move the choke-valve l3 toward closed position.

During the operation of cranking the engine, the magnet 3| will be energized, and will draw the armature 30 downwardly. Because of its engagement with the pin 53 on the link 5|, the armature, in moving downwardly, will swing the link 5| about its axis of pivotal connection to the arm 50, or to the full-line position illustrated in Fig. 4. This downward movement of the link 5| will move the choke-valve l3 toward closed position. Downward movement of the armature 30 is limited by its engagement with the pole of the magnet 3|, and therefore the position of the choke-valve when the magnet 3| is energized depends upon the position of the arm 50. If the engine is cold when cranked the inner end of the link 5| will be higher than if the engine is hot, with the result that the choking efiect produced is less when the engine is hot than when it is cold.

It will thus be seen that the device illustrated in Fig. 4, under the control of a single thermostat, limits the extent to which the choke-valve is closed during the operation of cranking the engine and limits the opening movement of the choke-valve after the cranking operation is completed.

It will be noted that in the device shown in Fig. 4 the thermostat is subjected to a distorting force when the magnet 3| is energized. In certain carburetors, where a considerable effort is necessary to close the choke-valve, the reaction on the element 35 may be sufficient to cause its permanent distortion. To prevent this, I may employ the arrangement illustrated in Fig. 5.

In the device illustrated in Fig. 5, the link 5|, instead of being directly connected to the thermostatically-controlled arm 50 is connected thereto through the intermediate member 60. As indicated in the drawings, the temperature-responsive element 35 and the arm 50 are conveniently located below the magnet 3|, the member 60 extending vertically upward beside such magnet and being pivotally connected at its upper end to the inner end of the link 5|. The arrangement of the thermostat 35 and the arm 50 illustrated in Fig. 5 is substantially the same as that of the correspondingly numbered parts in Fig. 4, the thermostat acting, under changes in temperature, to control the angular disposition of the arm 50. In this instance, the link 5| is of magnetic material to serve as an armature for the magnet 3|. The link 5|, from its point of pivotal attachment to the member 60, extends outwardly across the upper pole of the magnet 3|, and its outer end is connected through suitable connecting mechanism 52 with the chokevalve I3 in such a way that the choke-valve will be moved toward closed position when the outer end of the link 5| is depressed.

The lower pole of the magnet 3| is provided with a pole-piece 62 which projects outwardly toward the member 60. The latter, like the link 5|, is of magnetic material in order to co-operate with the link 5| in providing a closed magnetic circuit between the two poles of the magnet.

Near its upper end, the member 60 is supported in a guide 63 so arranged as to permit a limited amount of swinging movement of the member 60. The connection of the member 60 to the arm 50 is of the pin-and-slot type to permit a slight movement of the member 60 toward or away from the pole-piece 62.

The parts are shown in Fig. 5 in the position they occupy when the engine is hot and is not being cranked. The position of the inner end of the link 5| is determined by the temperatureresponsive element 35, and the spring l4 holds the choke-valve l3 in open position. When the engine stops and begins to decrease in temperature, the temperature-responsive element 35 swings the arm 50 in a clockwise direction to raise the inner end of the link 5|. The same screw 56 which has been described in connection with the device illustrated in Fig. 4 acts as a fulcrum for the link 5| with the result that clockwise movement of the arm 50 lowers the outer end of the link 5| and moves the choke-valve |3 towards closed position.

When the starter switch H3 is closed to actuate 75 the starter motor [1, the electro-magnet 3| is energized and drawsthe link 5| downward until it strikes the upper pole of the magnet. Simultaneously, the member 60 is drawn into engage- 'ment with the pole-piece 62, thus preventing the imposition of a distorting force on the temperature-responsive element 35. The extent to which the choke-valve E3 is moved toward. closed position when the magnet 31 is energized depends upon the position of the inner end of the link 5|, which in turn depends upon the position of the arm 5!], the arrangement being such that the choke-valve is moved more nearly to closed position when the engine is cold than when it is hot.

In the arrangement illustrated in Fig. 6, the joint control of the choke-valve with the startermotor is effected through mechanical rather than electrical means. In this arrangement, the thermostat 20 and control member 23 are employed as shown in Fig. 1. The choke-valve I3 is operatively connected to a longitudinally slidable member 65 having at its opposite end a pin 66 which is received in a cam slot 61 similar in purpose to the cam slot 25 illustrated in Fig. 1. The choke-valve l3 has associated with it the spring I4 which tends to move the choke-valve toward open position. Movement of the chokevalve under the influence of the spring I4 is limited by engagement of the pin 66 with the :right-hand side of the cam slot 61, this side of the cam slot being so shaped as to increase the extent of choke-valve opening as the temperature-responsive element 20 responds to increased engine temperature.

For the purpose of closing the choke-valve during the starting operation, I provide a rod 68 which is connected to the starter pedal to be moved to the left when the starter pedal is depressed to close the starter switch l8. The rod 68 is yieldingly connected to the choke-valve l3 as by means of a compression spring ll] which acts between an abutment H on the rod 68 and an arm 12 movable with the choke-valve.

In the device illustrated in Fig. 6, depression of the starter pedal 69 will move the rod 68 to the left, thus causing the spring It] to bear against the arm 12 to move the choke-valve 13 toward closed position. Movement of the choke-valve in this direction, however, is limited by engagement of the pin 66 with the left-hand side of the slot 61. Thereafter, the spring ill will be compressed to permit such movement of the starter pedal 69 as is necessary to close the switch I 8.

As in the devices previously described, the device illustrated in Fig. 6 embodies a single thermostat which controls both the extent to which the choke-valve is closed when the starter is energized and the extent to which the chokevalve opens after the cranking operation.

In the arrangement illustrated in Fig. '7, joint control of the choke-valve with the starter is eliminated, the choke-valve being arranged to be under manual control by a Bowden wire 15 which has a lost-motion connection with the arm 12. The same temperature-responsive element 20 and control member 23 are employed as are shown in Figs, 1 and 6. The control member 23 has a cam slot 25 which, by co-operation with the pin 66 and the member 65, limits the extent to which the choke-valve may be opened under the influence of the spring M or the extent to which it can be closed by operation of the Bowden wire 15. As in the other modifications, the slot 25 is shaped to provide for greater opening and less closing of the choke-valve as the engine temperature increases.

I claim as my invention:

1. In combination with an internal combustion engine having a carburetor provided with a choke-valve having a control member, mechanism for limiting both opening and closing movements of said choke-valve, said mechanism including abutments between which said control member is received and which define the limits of choke-valve movement, and a single temperature-responsive means responsive to engine temperature for moving said abutments simultaneously to increase the extent to which the chokevalve may be opened and to decrease the extent to which it may be closed as the temperature of the engine increases.

2. In combination with an internal combustion engine having a carburetor provided with a choke-valve having a control member, mechanism for limiting both opening and closing movements of said choke-valve, said mechanism including abutments between which said control member is received and which define the limits of choke-valve movement, and a single temperature-responsive means for jointly adjusting the respective positions of said abutments.

3. In combination with an internal combustion engine having a carburetor provided with an adjustable mixture-proportioning device having a control member, mechanism having abutments between which said control member is received for limiting adjustment of said mixture-proportioning device in both directions, and a single temperature-responsive means for jointly adjusting said abutments to control simultaneously both limits of adjustment of said mixture-proportioning device.

4. In combination with an internal combustion engine, means for forming an explosive mixture for said engine, said mixture-forming means being adjustable to vary the proportions of the mixture formed, provisions for confining such adjustment between upper and lower limits, a single temperature-responsive means responsive to engine temperature operating said provisions to control simultaneously such upper and lower limits of adjustment of said mixture-forming means, and adjusting mechanism connected to said mixture-forming means independently of said temperature-responsive means and of said provisions for adjusting said mixture-forming means between the limits established by said provisions.

5. In combination with an internal combustion engine, means for forming an explosive mixture for said engine, said mixture-forming means being adjustable to vary the proportions of the mixture formed, provisions for confining such adjustment between upper and lower limits, a single temperature-responsive means operating said provisions to control simultaneously such upper and lower limits of adjustment of said mixture-forming means, and adjusting mechanism connected to said mixture-forming means independently of said temperature-responsive means and of said provisions for adjusting said mixtureforming means between the limits established by said provisions.

6. In combination with an internal combustion engine having a carburetor provided with a choke-valve having a control member, yielding means for moving said choke-valve toward open position, said choke-valve being movable toward closed position in opposition to said yielding 75 means, adjustable provisions including abutments between which said control member is received for limiting both opening and closing movements of said choke-valve, and a single temperatureresponsive device for adjusting said provisions to control simultaneously both limits of movement of said choke-valve.

7. A device for controlling the choke-va1ve of an internal combustion engine carburetor, com- 10 prising a movable member adapted to be connected to the choke-valve, electro-magnetic means for moving said member in a direction to close said choke-valve, adjustable provisions for limiting movement of said member in both directions, and a single-temperature responsive device for adjusting said provisions to control simultaneously both limits of movement of said movable member.

GLEN R. SISSON. 

